"One has to distinguish natural selection for something and natural selection of something.

Natural selection did not select our blood to be red. It selected it for hemoglobin perhaps which happens to be red, but the redness itself was not selected. One of the problems of understanding evolution is deciding what characters are epiphenominal accidental consequences of things, and which are the direct objects of natural selection. All we can do there is tell stories."

Richard Lewontin